drm_hwcomposer: Don't compile all importers at once

Choose based on the BoardConfig flags.

I'd like to revert this once drm_gralloc is available
in all working branches.

Change-Id: I171d8f9146bdca0f0671092b8e539031c2f64f0f
Signed-off-by: Sean Paul <seanpaul@chromium.org>
diff --git a/Android.mk b/Android.mk
index 8024900..9fc17fa 100644
--- a/Android.mk
+++ b/Android.mk
@@ -26,7 +26,6 @@
 	libutils \
 
 LOCAL_C_INCLUDES := \
-	external/drm_gralloc \
 	external/libdrm \
 	external/libdrm/include/drm \
 	system/core/include/utils \
@@ -42,18 +41,19 @@
 	drmconnector.cpp \
 	drmcrtc.cpp \
 	drmencoder.cpp \
-        drmgenericimporter.cpp \
 	drmmode.cpp \
 	drmplane.cpp \
 	drmproperty.cpp \
 	hwcomposer.cpp \
-        nvimporter.cpp \
 	vsyncworker.cpp \
 	worker.cpp
 
 ifeq ($(strip $(BOARD_DRM_HWCOMPOSER_BUFFER_IMPORTER)),nvidia-gralloc)
+LOCAL_SRC_FILES += nvimporter.cpp
 LOCAL_CPPFLAGS += -DUSE_NVIDIA_IMPORTER
 else
+LOCAL_C_INCLUDES += external/drm_gralloc
+LOCAL_SRC_FILES += drmgenericimporter.cpp
 LOCAL_CPPFLAGS += -DUSE_DRM_GENERIC_IMPORTER
 endif